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Influences of chemical reactions on polysulfide reduction reaction process on promotor surface in Li-S batteries

Nano Research 2024年第4期17卷 2712-2718页

作者： Yufeng Luo Zhenhan Fang Zixin Hong Shaorong Duan Haitao Liu Hengcai Wu Qunqing Li Yuegang Zhang Shoushan Fan Wenhui Duan Jiaping Wang Tsinghua-Foxconn Nanotechnology Research Center Tsinghua UniversityBeijing 100084China Department of Physics Tsinghua UniversityBeijing 100084China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Frontier Science Center for Quantum Information Tsinghua UniversityBeijing 100084China

Polar promotors have been proven effective in catalyzing the polysulfide(PS)reduction reaction(PSRR)process in lithium-sulfur(Li-S)***,the promotor surface tends to be poisoned due to the accumulation of insoluble discharging products of lithium disulfide(Li_(2)S_(2))and lithium sulfide(Li_(2)S)during Li-S battery ***,we investigate the detailed PSRR mechanism on the surface of manganese sulfides(MnS)as a representative promoter by performing in-situ Raman mapping *** catalytic ability of MnS enables thorough electrochemical reduction of PSs to Li_(2)S_(2) and Li_(2)S on the MnS *** generated Li_(2)S_(2) and Li_(2)S then adsorb the dissolved PSs via chemical reactions among sulfur species during the subsequent PSRR *** phenomenon mitigates promotor poisoning and continuously improves the reversible ***,the assembled Li-S cell demonstrates excellent electrochemical performance after introducing a conductive interlayer containing a thin piece of carbon nanotube film and MnS promotors.

关键词： promotors polysulfides chemical reactions catalytic ability in-situ Raman measurements

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A charged hadronic string model within the R.P. Feynman proper time paradigm and vacuum field theory approach 14

A charged hadronic string model within the R.P. Feynman prop...

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14th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields, IARD 2024

作者： Bogolubov, Nikolai N. Prykarpatski, Anatolij K. ICTP Trieste Italy Department of Applied Mathematics The Cracov University of Technology Kraków Poland Department of Computational Mathematics and Programming The Lviv Polytechnic National University Lviv Ukraine

We study a novel charged hadronic string model within the least action principle and the vacuum field theory approach based on the classical R.P. Feynman’s proper time paradigm. It is stated that the hadronic string model allows the conformal local coordinates, with respect to which the resulting string dynamics is described by means of the linear second order elliptic equation under the Dirac type constraint, suitable for the canonical quantization and demonstrating a related gauge type invariance of the model. The related Lagrangian and Hamiltonian aspects of the string model, interacting with ambient both electrical and electromagnetic potential fields, are analyzed in detail. © 2025 Institute of Physics Publishing. All rights reserved.

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A LINEAR-COMPLEXITY TENSOR BUTTERFLY ALGORITHM FOR COMPRESSING HIGH-DIMENSIONAL OSCILLATORY INTEGRAL OPERATORS

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Multiscale Modeling and Simulation 2025年第2期23卷 864-893页

作者： Michael Kielstra, P. Shi, Tianyi Luo, Hengrui Qian, Jianliang Liu, Yang Department of Mathematics University of California BerkeleyCA94720 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Statistics Rice University HoustonTX77251 United States Department of Mathematics Department of CMSE Michigan State University East LansingMI48824 United States

This paper presents a multilevel tensor compression algorithm called tensor butterfly algorithm for efficiently representing large-scale and high-dimensional oscillatory integral operators, including Green's functions for wave equations and integral transforms such as Radon transforms and Fourier transforms. The proposed algorithm leverages a tensor extension of the so-called complementary low-rank property of existing matrix butterfly algorithms. The algorithm partitions the discretized integral operator tensor into subtensors of multiple levels and factorizes each subtensor at the middle level as a Tucker-type interpolative decomposition, whose factor matrices are formed in a multilevel fashion. For a d-dimensional (d > 1) integral operator discretized into a 2d-mode tensor with n2d entries, the overall CPU time and memory requirement scale as O(nd), in stark contrast to the O(nd log n) complexity of existing matrix algorithms such as matrix butterfly algorithms and fast Fourier transforms (FFTs), where n is the number of points per direction. When comparing with other tensor algorithms such as quantized tensor train (QTT), the proposed algorithm also shows superior CPU and memory performance for tensor contraction. Remarkably, the tensor butterfly algorithm can efficiently model high-frequency Green's function interactions between two unit cubes, each spanning 512 wavelengths per direction, which represents problems of scale over 512× larger than that existing butterfly algorithms can handle, with the same amount of computation resources. On the other hand, for a problem representing 64 wavelengths per direction, which is the largest size existing algebraic matrix algorithms can handle, our tensor butterfly algorithm exhibits 200x speedups and 30× memory reduction compared with existing ones. Moreover, the tensor butterfly algorithm also permits O(nd)-complexity FFTs and Radon transforms up to d = 6 dimensions. Copyright © by SIAM.

关键词： Fast Fourier transforms

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Machine learning potential assisted exploration of complex defect potential energy surfaces

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npj computational Materials 2024年第1期10卷 3017-3023页

作者： Chao Jiang Chris A.Marianetti Marat Khafizov David H.Hurley Computational Mechanics and Materials Department Idaho National LaboratoryIdaho FallsID 83415USA Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA Department of Mechanical and Aerospace Engineering The Ohio State UniversityColumbusOH 43210USA Materials Science and Engineering Department Idaho National LaboratoryIdaho FallsID 83415USA

Atomic-scale defects generated in materials under both equilibrium and irradiation conditions can significantly impact their physical and mechanical *** the energetically most favorable ground-state configurations of these defects is an important step towards the fundamental understanding of their influence on the performance of materials ranging from photovoltaics to advanced nuclear ***,using fluorite-structured thorium dioxide(ThO_(2))as an exemplar,we demonstrate how density functional theory and machine learning interatomic potential can be synergistically combined into a powerful tool that enables exhaustive exploration of the large configuration spaces of small point defect *** study leads to several unexpected discoveries,including defect polymorphism and ground-state structures that defy our physical *** physical origins of these unexpected findings are elucidated using a local cluster expansion model developed in this work.

关键词： properties defect potential

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Improved error estimates for a modified exponential Euler method for the semilinear stochastic heat equation with rough initial data

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Science China mathematics 2024年第12期67卷 2873-2898页

作者： Xinping Gui Buyang Li Jilu Wang Beijing Computational Science Research Center Beijing 100193China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina School of Science Harbin Institute of TechnologyShenzhen 518055China

A class of stochastic Besov spaces BpL^(2)(Ω;˙H^(α)(O)),1≤p≤∞andα∈[−2,2],is introduced to characterize the regularity of the noise in the semilinear stochastic heat equation du−Δudt=f(u)dt+dW(t),under the following conditions for someα∈(0,1]:||∫_(0)^(t)e−(t−s)^(A)dW(s)||L^(2)(Ω;L^(2)(O))≤C^(t^(α/2))and||∫_(0)^(t)e−(t−s)^(A)dW(s)||_B^(∞)L^(2)(Ω:H^(α)(O))≤C..The conditions above are shown to be satisfied by both trace-class noises(withα=1)and one-dimensional space-time white noises(withα=1/2).The latter would fail to satisfy the conditions withα=1/2 if the stochastic Besov norm||·||B∞L^(2)(Ω;˙H^(α)(O))is replaced by the classical Sobolev norm||·||L^(2)(Ω;˙Hα(O)),and this often causes reduction of the convergence order in the numerical analysis of the semilinear stochastic heat *** this paper,the convergence of a modified exponential Euler method,with a spectral method for spatial discretization,is proved to have orderαin both the time and space for possibly nonsmooth initial data in L^(4)(Ω;˙H^(β)(O))withβ>−1,by utilizing the real interpolation properties of the stochastic Besov spaces and a class of locally refined stepsizes to resolve the singularity of the solution at t=0.

关键词： semilinear stochastic heat equation additive noise space-time white noise exponential Euler method spectral method strong convergence stochastic Besov space real interpolation

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Paddy Yield Forecasting using Regression Techniques 2

Paddy Yield Forecasting using Regression Techniques

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2nd Edition of IEEE Delhi Section Owned Conference, DELCON 2023

作者： Chandrakumar, T. Avanthica Sri, M.A. Mirdula, K. Monika, K. Thiagarajar College of Engineering Department of Applied Mathematics and Computational Science TamilNadu Madurai India

ISBN: (纸本)9798350322064

India is one of the well-known countries whose socioeconomic position is heavily influenced by agriculture. Plant and livestock cultivation are the most important practices in agriculture. The cultivation of food surpluses enables people to live in cities. Agriculture employs over 70 percent of Tamil Nadu's population. It is a key source of income in Tamil Nadu. Paddy cultivation is significant as it is the main food for the majority of the Indians. The dataset used for this study includes various varieties of paddy grown in the Madurai district of Tamil Nadu. The dataset includes average paddy crop yield, Madurai taluks, soil type, soil pH, nitrogen, temperature, duration, and rainfall. This paper compares different regression algorithms and suggests an optimal algorithm that is used in a ML (Machine Learning) model that forecasts paddy yield. The machine learning regression techniques are multiple linear regression, lasso regression, and ridge regression. This paper concludes by discussing future work topics and the suitable algorithm to be employed in the model for yield prediction of a paddy crop. © 2023 IEEE.

关键词： Crops

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Fourier Continuation Discontinuous Galerkin Methods for Linear Hyperbolic Problems

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Communications on applied mathematics and Computation 2023年第4期5卷 1385-1405页

作者： Kiera van der Sande Daniel Appelö Nathan Albin Department of Applied Mathematics University of Colorado BoulderBoulderCOUSA Department of Computational Mathematics Science&EngineeringMichigan State UniversityEast LansingUSA Department of Mathematics Michigan State UniversityEast LansingUSA Department of Mathematics Kansas State UniversityManhattanKSUSA

Fourier continuation(FC)is an approach used to create periodic extensions of non-periodic functions to obtain highly-accurate Fourier *** methods have been used in partial differential equation(PDE)-solvers and have demonstrated high-order convergence and spectrally accurate dispersion relations in numerical *** Galerkin(DG)methods are increasingly used for solving PDEs and,as all Galerkin formulations,come with a strong framework for proving the stability and the *** we propose the use of FC in forming a new basis for the DG framework.

关键词： Discontinuous Galerkin Fourier continuation(FC) High order method

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Phase-field simulations of the effect of temperature and interface for zirconiumδ-hydrides

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Chinese Physics B 2024年第4期33卷 701-710页

作者：陈子航盛杰刘瑜施小明黄厚兵许可王越超武帅孙博刘海风宋海峰 School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Department of Physics University of Science and Technology BeijingBeijing 100083China

Hydride precipitation in zirconium cladding materials can damage their integrity and *** temperature and material defects have a significant effect on the dynamic growth of *** this study,we have developed a phasefield model based on the assumption of elastic behaviour within a specific temperature range(613 K-653 K).This model allows us to study the influence of temperature and interfacial effects on the morphology,stress,and average growth rate of zirconium *** results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride *** ultimate determinant of hydride orientation is the loss of interfacial coherency,primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree *** escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical,accompanied by the onset of redirection ***,redirection occurs at a critical mismatch level,denoted as qc,and remains unaffected by variations in temperature and interfacial ***,this redirection leads to an increase in the maximum stress,which may influence the direction of hydride crack *** research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

关键词： zirconium hydride phase-field method temperature effect mismatch degree

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Global weak solutions to a phase-field model for motion of grain boundaries

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applied mathematics and Mechanics(English Edition) 2022年第11期43卷 1777-1792页

作者： Zixian ZHU Boling GUO Shaomei FANG Department of Mathematics Shanghai UniversityShanghai 200444China Institute of Applied Physics and Computational Mathematics Beijing 100088China College of Mathematics and Information South China Agricultural UniversityGuangzhou 510642China

We employ the Galerkin method to prove the global existence of weak solutions to a phase-field model which is suitable to describe a sort of interface motion driven by configurational *** higher-order derivative of unknown S exists in the sense of local weak derivatives since it may be not summable over the original open *** existence proof is valid in the one-dimensional case.

关键词： solid-solid phase transition phase-field model Galerkin method weak solutions

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A Novel Segment White Matter Hyperintensities Approach for Detecting Alzheimer

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Computer Systems Science & Engineering 2023年第3期44卷 2715-2726页

作者： Antonitta Eileen Pious U.K.Sridevi Department of Science and Humanities Sri Krishna College of Engineering and TechnologyCoimbatore641008India Department of Applied Mathematics and Computational Sciences PSG College of TechnologyCoimbatore641008India

Segmentation has been an effective step that needs to be done before the classification or detection of an anomaly like Alzheimer’s on a brain *** helps detect pixels of the same intensity or volume and group them together as one class or region,where in that particular region of interest(ROI)can be concentrated on,rather than focusing on the entire *** this paper White Matter Hyperintensities(WMH)is taken as a strong biomarker that supports and determines the presence of Alzheimer’*** thefirst step a proper segmentation of the lesions has to be carried *** pointed out in various other research papers,when the WMH area is very small or in places like the Septum Pellucidum the detection of the lesion is hard *** overcome such problem areas a very optimized and accurate Threshold would be required to have a precise segmentation to detect the area of *** would help in proper detection and classification of the *** this paper an elaborate comparison of various thresholding techniques has been done for segmentation.A novel idea for detection of Alzheimer’s has been presented in this paper,which encompasses the effectiveness of an optimized and adaptive *** Unet architecture has been taken as the baseline model with an adaptive kernel model embedded within the *** state-of-the-art technologies have been used with the dataset and a comparative study has been presented with the current architecture used in the *** lesion segmentation in narrow areas has accurately been detected compared to the other models and the number of false positives has been reduced to a great extent.

关键词： Alzheimer’s adaptive threshold deep learning segmentation

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